Process of electrically depositing aluminium



NITED STATES PATENT OFFICE.

GLEN LENARDO WILLIAMS, OF NEW YORK, N. Y., ASSIGNOR, BY 'MESNE ASSIGN- MENTS, CPO/HENRY WALTON CAMPBELL, 0F DETROIT, MICHIGAN.

PROCESSOF ELECTRICALLY IDEPOSITING ALUMINIUM.

No Drawing.

To all whom it may concern:

Be it known that I, GLEN LENARDO WIL- LIAMS, a citizen of the United States, residing at New York city, in the county of New York, State of New York, have invented certain new and useful Improvements in Processes of Electrically Depositing Aluminium, of which the following is a specification.

This invention relates to a process of producing aluminium from a solution of a compound thereof in a normally liquid electrolyte by the action of electricity and has for its object the production of aluminium in a direct and economical manner from normally liquid or liquefied substances without the necessity of utilizing a fused electrolyte or vehicle therefor as employed hitherto and it comprises liquefying or dissolving an aluminium compound such as aluminium sulfate by or in liquid sulfuric acid of substantially anhydrous character such a substance comprising sulfuric acid containing free sulfuric anhydrid commonly known as oleum containing ap proximately 85% of sulfuric anhydrid (S0 and which readily dissolves 10% of aluminium sulfate, and exposing the alu- Ininium sulfate therein to an electrolysis preferably employing a current of approximately 3 volts with a cathode of aluminium and an anode of graphite and adding fresh aluminium sulfate or substance capable of forming the same such as aluminium oxid or hydroxid to the sulfuric acid as it becomes depleted of aluminium by electrolysis. 7

As an example of the process and manner in which the same is carried out, the production of aluminium from its sulfate by electrolysis will be taken.

A suitable electrolytic bath or electrolytic vehicle is rovided such as the substance commonly nown as oleum comprising anhydrous sulfuric acid containing sulfuric anhydrid in which is suspended electrodes, the cathode of which comprises aluminium and the anode of which comprises graphite.

To this oleum or electrolyte vehicle, comprising substantially sulfuric acid containing 85% of sulfuric anhydrid (S0 is rimarily added and dissolved therein 7 Specification of Letters Patent.

Patented Aug. 31, 1920.

Application filed March 11, 1918. Serial No. 221,736.

aluminium sulfate which is decomposed by the electric current depositing aluminium at the cathode and generating sulfuric anhydr1d at the anode which sulfuric anhydrid dissolves in the oleum electrolyte vehicle.

As the oleum vehicle becomes depleted of alumlnium by its deposition through electrolys1s, aluminium hydroxid or hydrated 0x101 is added to the oleum electrolytic vehiclefrom time to time to supply. a fresh Ll11 H11Il1U.1Il COII1pOU.I1d as electrolyte, and which aluminium hydroxid or hydrated oxid is immediately seized by the sulfuric anhydrld present in the oleum converting it into new and fresh aluminium sulfate in accordance with the following chemical formula or equation:

in its solution in oleum reduces the elec-' trical resistance so that its electrolysis may be carried on at a voltage at which oleum per so would be too highly resistant to allow the transmission of the electric current so that the aluminium sulfate may be electrolytically decomposed or disassociated at a voltage below that at which the oleum electrolyte vehicle or solvent is electrolytically afiected so that if the tension of the current is maintained at substantially three volts, the aluminium compound is only decomposed to the exclusion of the oleum so long as any aluminium' compound such as aluminium sulfate is contained in the electrolyte solvent of vehicle oleum and the process may be carried on continuously so long as the oleum contains or is supplied with aluminium sulfate with an electric cur-- rent of substantially low voltage in the yielding of aluminium. I

There have been many suggestions in the prior art for the electrolytic deposition of aluminium from its compounds while dissolved in an aqueous vehicle, but it has been found that instead of yielding aluminium at the cathode, such aluminium as would be deposited at that point becomes immediately oxidized by the water present, and converted into aluminium hydroxid or hydrated oxid which then immediately dissolves in the solution through the solvent action of the aqueous acid or alkaline electrolyte vehicle and for this reason such processes have not been commercially adaptable.

In the present case it will be seen that the acid electrolyte vehicle oleum has no free water to act as a preliminary oxidant whereby the aluminium deposited as metal may be converted into an aluminium compound soluble in the acid, and inasmuch as alumlnium per se is insoluble in oleum it maybe deposited electrolytically from a solution of its compound therein, and not be re-dlssolved'a'fter it is deposited.

It is advisable in order to facilitate the solution or liquefaction of the aluminium compound electrolyte such as aluminium sulfate in the oleum vehicle, reduce the electrical resistance of the composition and obtain lar er yields in shorter time than the liquid e ectrolyte and its vehicle be heated to a temperature of 100 degrees C- or to a point at which free water would be ordinarily evolved and dissipated.

Having now described my invention what I claim is:

1. The process of producing aluminium which comprises electrolyzing an aluminium compound while dissolved in a normally liquid anhydrous vehicle inert to aluminium and of higher electrical resistance than the aluminium compound to be electrolyzed.

2. The process of producing aluminium which comprises electrolyzing an aluminium compound while dissolved in a normally liquid anhydrous acid vehicle inert to aluminium to be electrolyzed.

v 3. The process of producing aluminium which comprises electrolyzing an aluminium compound while dissolved in a normally liquid anhydrous sulfuric acid vehicle inert to aluminium and of higher electrical resistance than the aluminium compound to be electrolyzed.

4. The process of producing aluminium which comprises electrolyzing an aluminium compound while dissolved in oleum.

5. The process of producing aluminium which comprises electrolyzing an aluminium sulfate while dissolved in a normally liquid anhydrous vehicle inert to aluminium and of higher electrical resistance than the aluminium sulfate to be electrolyzed.

6. The process of producing aluminium which comprises electrolyzing an aluminium sulfate while dissolved in a normally liquid anhydrous acid vehicle inert to aluminium sulfate to be electrolyzed.

7 The process of producing aluminium which comprises electrolyzing an aluminium sulfate while dissolved in a normally liquid anhydrous sulfuric acid vehicle inert to aluminium and' of higher electrical resistance than the aluminium sulfate to be electrolyzed.

8. The process of producing aluminium which comprises electrolyzing an aluminium sulfate While dissolved in. oleum 9. The process of producing aluminium which comprises electrolyzing an aluminium compound while dissolved in a normally liquid anhydrous vehicle inert to aluminium and of higherelectrical resistance than the aluminium compound to be electrolyzed while in a heated condition.

10. The process of producing aluminium which comprises electrolyzing an aluminium compound while dissolvedv in a normally liquid anhydrous acidvehicle inert to aluminium to be electrolyzed while in a heated condition. y

11. The process-of producing aluminium which comprises electrolyzing an aluminium compound while dissolved in a normally liquid anhydrous sulfuric acid vehicle inert to aluminium and of higher electrical resistance than the aluminium compound to be electrolyzed, while in a heated condition.

12. The process of producing aluminium which comprises electrolyzing an aluminium sulfate while dissolved in oleum while in a heated condition.

13. The process of producing aluminium which comprises electrolyzing an aluminium sulfate while dissolved in a normally liquid anhydrous vehicle inert to aluminium and of higher electrical resistance than I the aluminium sulfate to be electrolyzed while in a heated condition.

14. The process of producing aluminium which comprises electrolyzing an aluminium sulfate while dissolved in a normally liquid anhydrous acid vehicle inert to aluminium sulfate to be electrolyzed while in a heated condition.

15. The process of producing aluminium I which comprises electrolyzing an aluminium? sulfate while dissolved in a normally liquid anhydrous sulfuric acid vehicle inert to aluminium and of higher electrical resistance than the aluminium sulfate to be electrolyzed while in a heated condition. y

16. The process of producing aluminium which comprises electrolyzing an aluminium sulfate while dissolved in oleum while in a heated condition.

17 In the process of electrolytically depositing aluminium from a normally liquid electrolyte, the step which comprises supplying the aluminium compound to be electrolyzed from time to time as the liquid vehicle becomes depleted thereof by electrolysis.

18. In the process of producing aluminium from a normally liquid electrolyte, the step which comprises producing the aluminium compound to be electrolyzed within, the liquid electrolytic vehicle by supplying thereto from time to time an aluminium compound capable of reacting with a constituent or constituents of the vehicle to produce the compound to be electrolyzed as the liquid vehicle becomes depleted, of the aluminium compound product, by electrolysis.

19. The process of producing aluminium which comprises supplying aluminium oxid or hydroxid to oleum electrolyzing the 10 product produced thereby therein and adding more aluminium oxid or hydroxid as the oleum? is depleted of aluminium by electrolysis.

In testimony whereof I affix my signature in the presence of tWo Witnesses.

GLEN LENARDO WILLIAMS L. 5.]

l/Vitnessesz PAUL R. NEWMAN, WILHELMINA M. LOTZ. 

